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By Biswas AK, Hayes P

During the reduction of iron oxide pellets in the blast furnace it has been found that catastrophic swelling (up to 300% volume increase) can occur. Although the burden preparation conditions can be designed to avoid this phenomenon the exact reason and mechanism of the swelling has yet to be clearly identified. Swelling of the burden is undesirable since it reduces the interparticulate voidage in the blast furnace thus reducing gas flow through the stack resulting in low production rates of iron. The present study differs significantly from previous experiments in that reduction is carried out on single crystals of wustite thus the problems of control of gas composition and specimen preparation are minimised. The microstructures formed on reduction have been examined by optical and scanning microscopy. Pure wustite and wustite doped with various levels of CaO have been examined after reduction in controlled CO-CO 2 gas mixtures at 968¦C. The catastrophic swelling on reduction coincides with the formation of an unusually open iron structure in which the iron appears as whiskers or needles as previously reported. The spacing and thickness of the needles are shown to vary with impurity content and gas composition. Metallographic examination has shown in addition, however, that the whiskers do not necessarily constitute the only product form of the iron produced and in CaO containing wustites with less than - 2% CaO there is a transition from needle growth to porous growth of iron. Thus the % swelling of the oxide particles is dependent on the initial size of the oxide grains. Samples of FeO - 10% CaO exhibited a previously unreported product inorphology associated with the nucleation of 2CaO.Fe203.

Jan 1, 1980

By Mercer J. K

Shaft guide reaetions in No. 2 Ore Shaft, Mount Isa Mines Limited, have been reduced to a low order of magnitude by the use of self aligning slippers and spring loaded guide rollers. Before commissioning the new 4500 h.p. winder at No. 2 Ore Shaft in January, 1958, it was realised that the increase in hoisting speed from 1800 to 2650 ft/min. would cause high shaft guide reactions which would be increased further when the elongated 12 ton skips replaced the existing 7 ton skips.The Cambridge accelerometer was used to measure the shaft guide reactions and to confirm that progressive skip modifications were resulting in reduced reactions. The skip modifications were completed in 4 weeks.INTRODUCTIONIn 1956 an expansion programme was initiated to increase production from 5000 to 11000 tons per mining day. At No. 2 Ore Shaft the 1500 h.p. winder operated at 1800 ft./min. and hoisted a 7 ton capacity skip. The new 4500 h.p. winder operates at 2650 ft./min. and hoists a 12 ton capacity skip. No. 2 Ore shaft is equipped with two 5 ft. by 5 ft. hoisting compartments (Fig. 1) and any increase in skip capacity meant an abnormally long skip. This feature, coupled with the increase in hoisting speed, could have caused very high shaft guide reactions. Before commissioning the 4500 h.p. winder, a Cambridge accelerometer was borrowed from the University of Adelaide and was used to measure the shaft guide reactions. Rather than carry out an extensive shaft timbering programme, the skips were modified by fitting cushioned guide shoes and spring loaded guide rollers (Fig. 1). Testing commenced in February, 1958, and was completed in March, 1958.

Jan 1, 1961

The Electricity Generating Authority of Thailand own and operate an opencut mine supplying coal to on-site power stations at Mae Moh, 600 km North of Bangkok. The mine is being expanded from an annual production of 1.5 million tonnes per year in 1982 to over 9.5 million tonnes per year by 1991. The mine will be amongst the largest open pit operations in the world. It is technically difficult to operate and plan due to complex geology, weak strata and surface constraints including reservoirs, forests and traditional villages. This paper presents a case study of mine planning for the above project including associated collection and processing of geological and geotechnical information. The existing operation is described, as well as the strategy adopted for the mine at expanded production. The planning covers various phases of mine planning including a Conceptual Study, a Definitive Study and detailed short term planning. Each stage incorporated new information and reflected a higher level of confidence in the data and resulting plan. Sophisticated computer techniques were required including geological modelling, calculation of volumes, geotechnical analysis, scheduling and costing. The planning was undertaken on site by a team of Australian and Thai Engineers as part of the Thailand-Australia Lignite Mines Development Project which is a four year programme of assistance funded by the Australian Government.

Jan 1, 1986

By Binns MJ

Gold/silver orebodies of the Golden Plateau deposit, Cracow, Central Queensland, are currently being exploited by the Cracow Mining Venture. A geostatistical block model has been prepared to assist with long term mine planning. The Golden Plateau orebody, of inferred epithermal origin, is a multiply brecciated, silicified fault complex containing irregular, tabular and pipe- like oreshoots. Historically the lode has been stoped and open cut over a strike length of 750 metres at widths of up to 15 metres and to a depth of 250 metres. The Golden Plateau mine produced 1.55 million tonnes of ore at an average grade of 12 g/t Au and 13.5 g/t Ag over a 42 year period. In the preparation of the reserve model much reliance has been placed on recent diamond and reverse circulation drilling (71 holes in total). However a significant volume of data has been derived from historical level assays and underground diamond drilling. Over 3,000 level assays and 50 underground drill holes contributed to the database. Similar lognormal populations were observed for 1 metre composite grades from each major drilling campaign once corrections were made for core loss. Cumulative frequency plots revealed only one outlier which was cut to the population line. The population statistics from the historical level assays showed a significant difference from those derived from the drill hole composites. Level assay populations were cut to local drill hole populations before incorporation into the ore reserve model. The resulting data has yielded interpretable variograms, the parameters of which have been applied to the preparation of a kriged block model of the deposit.

Jan 1, 1987

Vatukoula is a gold mining township situated at the south-west periphery of a Tertiary caldera which measures 3 miles by 4 miles. Erosion of the caldera resulted in the formation of a topographic depression, called the Tavua basin, covering about 30 square miles. This area, also known as the Tavua Goldfield, has been the site for spasmodic prospecting since the initial discovery of gold in 1932.The mineralization at Vatukoula is typically epithermal with the gold occurring as tellurides, auriferous sulphides, and to a much less extent as native gold. The lodes are confined to three major structures i.e. north-west shears, flatly dipping structures (flat makes), and local shatter orebodies.Within these structures, at least five types of controls are recognized to account for the localization of the oreshoots. The dominant control is structure.The lode structures are related to the overall structural pattern of the Tavua basin. This pattern, which is controlled by the collapse planes of the caldera and a north-west shear system, produced a "shatter block" atVatukoula and elsewhere around the caldera.Structural analysis indicates there are certain areas in the Tavua basin where exploration could be rewarded by the discovery of orebodies with similar controls to those of the productive Vatukoula block.

Jan 1, 1967

New Zealand's Land and Income Tax Act 1954 contains unique incentives for companies engaged in mining certain specified minerals or petroleum. Sections 152 and 153 provide for the taxable income of such companies to be based not on profits made but on dividends paid to shareholders. A significant saving in tax results, particularly where profits are not distributed: but the Act attempts to ensure that undistributed profits are used for further mineral exploration and development. To encourage investment in the mining industry, persons taking up shares in a company mining for the specified minerals or petroleum are entitled to a one-third deduction in respect of monies paid on the shares and used by the company for its purposes; and company shareholders may make loans to the company and write-off such loans for tax purposes to an amount of up to half their taxable income. Maximum utilisation of the tax incentives calls for careful consideration as to whether a mining or petroleum company should be financed by way of loan capital or share capital.

Jan 1, 1971

By S M. C Verryn

Through the application of the Rietveld method, X-ray diffraction analysis has developed into a fully quantitative method for phase analysis of metallurgical products. The Rietveld method itself has progressed from an unstable method that required constant operator intervention to a stable and robust method suited even for routine process control. Knowledge of the crystal structures of the major phases is essential for Rietveld analysis, and these are well known for most minerals and major phases in metallurgical products. It provides the basic structural information necessary for the determination of mineral stoichiometry and for elucidating solid solution behaviour. Modern methods, such as simulated annealing and charge flipping, permits the determination of crystal structures from powder data. Unit cell data can be used where conventional microchemical analysis is unable to provide an answer to the extent of solid solution in ilmenite roasting. Unit cell data (by XRD) is used to determine the amount of roasting necessary for the development of magnetisation to be able to separate chromite from an ilmenite concentrate. Phase quantification is probably the most widely used application of XRD analysis. It is used for materials balance in the minerals and cement industries, and it is finding novel applications in the iron and steel industry. Applications of XRD in high-temperature metallurgical processes are increasing. In this paper the phase chemistry of iron ore sinters, the evaluation of subsolidus reactions in titania slags and the identification of furnace accretions are discussed. Despite the success of the Rietveld method in phase quantification, the method still needs further development in the quantification of closely related or polytypic phases. The quantification of pyrrhotite phases using various Rietveld programs still gives ambiguous results. This is also true for the different SFCA phases in iron ore sinters. Clearly the analysis of similar phases, differing only in the presence of weak superlattice reflections is still problematic.

Jan 1, 2008

By Dierling D. H

The paper briefly describes the mining system employed on Western Deep Levels for the past 20 years. The negative aspects which gave rise to a new mechanized method of mining are discussed. The sequence of events leading from the Mine's first attempt at trackless mining in 1980 to the present day in-stope project is presented. The original justification for this project and the in-stope trackless mining method is described in detail. The results to date are evaluated and the original rationale for going in-stope trackless mining questioned. A totally new mining philosophy for Western Deep Levels, whereby major geological disturbances are left in situ and longwalls re-established and mined using trackless mining machinery is described. The economics of this mining method are discussed. Trackless mining machinery can also be put to good use within the conventional longwalls in a new method of mining using Load Haul Dumpers (LHD) in reef drives. When the instope trackless mining project commenced in 1983, it was stated that expansion to any significant degree with diesel powered vehicles could be ruled out and electrically driven alternatives would have to be developed. This issue is discussed and the Mine's decision to expand with diesel powered vehicles explained. Finally, the extent to which trackless mining is likely to be seen in the 1990 s at Western Deep Levels is discussed.

Jan 1, 1986

By Propser M, Szekely J

Flow maldistribution in the iron blast furnace has been studied analytically by the use of the vectorial form of the Ergun equation and experimentally via packed columns and a cold model of a blast furnace. Experimental results are presented showing the effect on fluid flow patterns of the following types of nonuniformities in a packed bed: the increased voidage at the wall ("wall effect"), the decreased voidage at the interface between layers of materials with different sizes and shapes, and the differences in resistance to flow of bulk regions of a column with different sizes and shapes. The proposed theory is applied to the calculation of fluid flow patterns for these nonuniformities. Velocity profiles, as calculated from these flow patterns, were found to agree reasonably well with experimental measurements obtained via hot wire anemometry techniques for laboratory scale packed columns. Calculated fluid flow patterns are presented for blast furnace burdens which show how flow patterns are affected by (a) coke segregation and (b) the relative differences in resistance to flow between coke and oxide pellet layers. For the cold model study, calculated flow patterns are presented based on photographs of a given burden distribution. The velocity profiles calculated from these flow patterns were found to agree reasonably well with the velocity profiles measured from the cold Model.

Jan 1, 1975

A method is presented for calculating the number of cycles of stress to failure of a drill rod from operating variables; a mathematical analysis by Cooper of the stresses present in drill steels is applied to the forged collar, i1i-in. hexagonal hollow drill steel in common use in Australia; and an estimation is made of the dry fatigue limits at various points along a drill rod.It is shown that these calculations predict failure at a 'point where failure rarely occurs, and do not predict that failure should occur where it does in practice. The reasons for this anomaly lie in the neglect of bending stresses in the stress calculations, and in failuredue to corrosion fatigue at a preferred section rather than to simpler fatigue under non-corrosive conditions.INTRODUCTIONIt has long been recognized that failure of metal sections by fatigue is influenced both by the number of cycles of stress imparted to the section (N) and by the magnitude of this cyclic stress (8). In this paper, both Nand Shave been calculated for rods which have failed in service, and whose operating history is known. While the calculation of the number of cycles to failure is·simple, the calculation of stress is more complex. The results of stress caIculations predict that failure should occur only hi short rods, and then preferentially at the tip end rather than the shank end.However, in actual fatigue failures of steel rock drill rods, approximately 75 per cent. of such failures are close to the shank end, and failures near the tip end are rare.The usual explanation given for this high incidence of shank-end failures is that at the point of failure there exists, in forged collar steels of the type common in Australia "hardness valley" or. "m'etallurgical notch". This narrow valley in hardness is a weakness, and failure is expected to occur at the weakest point at the bottom of...

Jan 1, 1955

By White A. H, Vihena M. T M B

Presently, orebody modelling consists basically of fitting a mathematical model to represent spatially a certain geological variable, generally grade. An orebody model is constructed from a set of sample data obtained from various locations in the orebody, thus it is only one form of representation of the true phenomena. Checking the compatibility of the data with the modelling procedure is the most important factor when assessing confidence in the orebody model. The level of confidence in the model will depend on the adequacy of the data set and the validity of the basic assumption required by the modelling method. Fractal geometry is one way of modelling the spatial distribution of a geological variable in an orebody geometry. Fractals can be used to interpolate the Z(x) geological variable at unsampled sites. The concepts of self similarity and self affinity that form the basic assumption of fractal geometry theory which areinvestigated. The population distribution of the geological variable in question must be examined to determine the appropriateness of both fractal geometry and geostatistical modelling methods. The selection of the most appropriate method depends on the available data. A researcher or a practitioner needs to understand the strengths and limitations of the various modelling methods before choosing the most appropriate method. This study investigates the fractal properties of grade distribution using the variogram and some proposed variations as techniques to measure the fractalness. The aim is to assess applicability of fractal geometry theory to modelling ore grade distribution in a deposit. A comparison of the results demonstrates the methods which better capture the spatial behaviour of the variable under study.

Jan 1, 1995

By Maxwell HW

Pacific Coal Pty Limited (a wholly owned subsidiary of CRA Limited) managed the interests of six members of a joint venture formed to mine and export eight million tonnes of export quality steaming coal from a mine developed at Blair Athol in the Bowen Basin of the Central Queensland coal fields. The mine is now operated by Blair Athol Coal Pty Ltd. Crooks Michell Peacock Stewart Pty Limited (CMPS) was awarded a project management and engineering contract for the total mine portion. Following a feasibility study, CMPS carried out an Optimisation Study which produced changes to the design of the project, thus resulting in the project budget being reduced by some A$13 million. In spite of a number of late additions to the scope of work, the project was completed at a final cost of A$148 million, many millions below the reduced project budget. The project was also completed several months ahead of schedule. Total services were provided to take the project from feasibility stage through to the establishment of an operational facility and included project management, planning and control, accounting and financial control, as well as the organisation of engineering, procurement, construction, industrial plant commissioning, and technical training matters.

Jan 1, 1986

By Miskelly N

In Australia and New Zealand, the 'Australasian Code for Reporting of Identified Mineral Resources and Ore Reserves', which was released by industry in 1989, is operating successfully in a co-operative approach between industry and regulatory authorities. Similar codes or guidelines exist or are under development in the United States of America, Canada, the United Kingdom and South Africa, although the regulatory backing given to the Australasian Code is unique. International standard definitions for Mineral Resources and Reserves, and for categories of Resources and Reserves, have been under development by the Council of Mining and Metallurgical Institutions since 1994 and have already stimulated considerable convergence of definitions and reporting standards in participating countries. It is hoped that agreement on this international standard for public reporting by mining companies will be reached within the next two years, and it is expected that adoption of the standard will result in a higher and more uniform quality of reporting worldwide, with a consequently greater interest on the part of the general public and financiers in investing in the mining industry.

Jan 1, 1997

By D Thornton

Geologists use large data sets and spend many hours and much computing time modelling the distribution of minerals throughout a rock mass. Significant investments in drilling, assaying and quality assurance and quality control (QA/QC) are made before sophisticated geostatistical techniques are applied to the collected data. A large amount of research has been done in this field such that the ore control model is a reasonably accurate reflection of the mineral that is actually in the ground. However, after all this effort, the mining engineers then work just as diligently to blast the in situ rock mass to a particle size that can be efficiently handled and further reduced by downstream comminution processes. In open cut mines, this invariably requires large amounts of explosive energy that displaces the ore boundaries from where the geologists originally defined them. Failure to accurately account for blast movement will result in misclassification, whether that is ore to waste; low grade to high grade; sulfide to oxide; or other contaminates û collectively referred to as ore loss and dilution. The financial consequence of getting this wrong is substantial and not well quantified. This diminishes all of the good geological QA/QC done in defining the ore. This paper discusses various technologies used to physically measure blast-induced orebody movement and the difficulties in modelling this with a purely theoretical approach. Rock mass structure, blast energy, design and timing contours all have significant and interrelated effects on blast movement vectors. Measured blast movement has a large variance due to the uncertainly of many of the controlling parameters û arguably dominated by the heterogeneous nature of the rock mass. Although there have been significant advances in blast movement modelling capability in recent years, this unpredictable blast movement limits their use in the context of production ore control. Certainly, without physical field measurements, accurate predictions of movement are near impossible.Limitations of traditional surface markers in determining three-dimensional (3D) blast movement within the orebody are also reviewed, and advancements in accurately measuring these vectors within blasted ore discussed

Sep 26, 2011

By Duran A, Eggers M. J

It is standard practice in geotechnical studies for mine design to drill a series of inclined oriented boreholes into the proposed pit walls. However, this investigation tool is often used without an adequate understanding of the inherent shortcomings in the method and the many potential sources of error. Of the more commonly used orientation methods in Australia the clay imprint technique is probably the most reliable. Contoured stereographic plots of oriented core data are frequently characterised by diverse pole distributions and low concentration maximums compared with line mapping data. Common sources of error producing these poor results are misinterpretation of orientation marks or imprints, inaccurate marking of the reference line, errors in the structural measurement of the defects, lack of continuity information and blind zones sub-parallel to the borehole direction which correction methods frequently do not fix. Line mapping is the preferred method of structural data collection due to the lower overall cost, availability of continuity information and higher accuracy. The projectability of field mapping data to final wall positions can be assessed with a good understanding of the regional geology and local structural patterns. Where field mapping is not possible due to a thick regolith cover, core orientation should be carried out by experienced personnel to minimise the many potential errors.A series of case studies are presented which compare oriented core with mapping and highlight the inherent problems with the technique.

Jan 1, 1992

By Campbell Brown G F

THE Mount Morgan mine has, from the time of its historical discovery, been the subject of investigation and speculation by geologists and mining engineers. The first examination was made by Dr. R. L. Jack, in 1884. He came to the conclusion, from theevidence then available, that nothing but a thermal spring in the open air-otherwise a geyser-could account for the formation of the ore body. This report attracted world-wide attention at the time. Since then the mine has been examined by most of the leading geologists of Australia, and by many from elsewhere. In all cases the examination has only extended over a period' of a few days or weeks, and in the light of present knowledge of the deposit we know that sufficient data could not be obtained in such a short time to warrant the statement of definite conclusions. It is not to be wondered at, therefore, that a considerable difference of opinion exists as to the genesis of the deposit. That the company considered more detailed investigation necessary is shown by the fact that some thirteen years ago it employed Mr. Charles Walker as geological surveyor on the .mine. At that time also the data available was insufficient to give satisfactory results. It is, however, a matter for comment that none of the geological reports on the property took notice of the increase of copper values in the ore with depth, though the present workings and diamond-drilling...

Jan 1, 1911

A thick sequence of alkaline intrusions and volcanic rocks underlies a Quaternary caldera on Liliir Island. The sequence is host to a still active sub-aerial hydrothermal system and associated epithermal gold mineralisation. Sub-horizontal alteration horizons exhibit progressively increasing chondrite norma-lised (La/Lu) en and (La/Sm) cn ratios from unaltered shoshonites, to the potassic alteration zone, to the argillic altera-tion zone to the advanced argillic alte-ration zone. The increasing fractionation of HEE, and especially of LHEE, up the alteration sequence is the result of de-creasing pH, temperature and alkalinity of the hydrothermal fluids with increa-sing alteration intensity. HRE3 were especially mobile in argillic and advanced argillic alteration units characterised by acid fluid conditions and large fluid volumes. Abundant Cl, S and CO2 within the hydrothermal fluids and thus abundant REE complexing agents and large fluid volumes favoured the mobility of REE during hydro-thermal alteration of the volcanic rocks and intrusions. Steam escape, mixing of the gases with groundwater and a change from a magmatic neutral chloride hydro-thermal system to a meteoric acid sulphate system was accompanied by liquid/vapour ratio changes, pronounced alkalinity, pH and temperature decreases, and fluid/rock ratio increases. This caused the mobili-sation, fractionation and deposition of PF.F.

Jan 1, 1990

Neutralisation, normally using lime, is the most widely used method for treating high flows of acid mine drainage (AMD). Lime costs can be very high however. If carbonate sources could be used to achieve pH values above six, costs could be greatly reduced. For example, use of locally quarried limestone at Mt Lyell could potentially reduce alkali costs from about $A 3.5 to $A 1 million/year. Methods for enhancing the effectiveness of limestone and magnesite for neutralising Mt Lyell and Savage River AMD respectively have been examined through a series of investigations. Small-scale testwork found that the maximum pH economically achievable with ground limestone was about five, due to slow dissolution rates and surface armouring. The problems of surface armouring were greatly reduced by the use of crushed limestone or magnesite at high pulp densities (75 per cent solids w/w), enabling pH values >6 to be achieved in a practical time frame. The use of particle sizes in the range 6 mm and finer also reduces costs by avoiding the need for grinding, and reduces the problems of solid-liquid separation and solid recycling that arise if large additions of ground carbonate are used. Pilot scale tests were carried out using tumbling drum reactors with limestone and Mt Lyell AMD and a pulsed-bed static reactor with magnesite and Savage River AMD. pH values averaging 6.2 and 6.4 were achieved with Mt Lyell and Savage River AMD respectively. Approximately 80 per cent of feed acidity was neutralised. A preliminary engineering design and cost estimate has been completed on the pulsed-bed reactor and shows that the concept is technically feasible and, if results are confirmed, economically attractive. Further pilot testing is planned.

Jan 1, 2002

By Abraham B. K, Jensen B, Gillies A. D S

The aim of the research was to investigate the feasibility of using an impedance cell and ratio-transformer bridge to measure solids content in coal slurry pipelines. It appeared that this technique could be developed to measure variations in conductance which correlate with solids content. Successful implementation of the measurement technique would have a variety of applications in existing coal wash plants and the potential for automatic process control. A small pilot plant was designed for a feasibility study. This was a closed loop system in which the coal was uniformly dispersed in a tank with a variable speed agitator and then circulated through an external pipe returning to the top of the tank. The impedance cell was located near the end of the external pipe. Slurry concentrations were varied from clean tap water to 50 per cent solids by weight with the addition of weighed quantities of dry coal dust. Ratio-transformer bridge measurements showed that variations in individual observations were equivalent to measurement errors of about two per cent. These probably reflect variations in concentration of the mixture in the pipe. Data for increments in concentration of one per cent indicate that this is about the limit of resolution of the current system. The paper discusses the principles of operation of the impedance cell and measurement system. Results from the pilot study and proposed improvements in the impedance cell design are examined.

Jan 1, 1995

By Harraway D. H, Draper N

The association of graphite with a fine grained pyrite in the Mount Isa lead-zinc ore was investigated from mineralogical and metallurgical standpoints. The pyrite has been partially or completely replaced by galena and to a less extent by sphalerite, pyrrhotiteand chalcopyrite with the retention of graphite films or inclusions. During lead flotation the graphite imparts a spontaneous flotability to all associated minerals, resulting in a low grade fraction, which we call the carbonaceous fraction, floating with and diluting the lead concentrate. In times of low metal prices this fraction seriously reduces the economic value of the lead concentrate. A flotation procedure was developed to upgrade the carbonaceous fraction separately, producing an economic concentrate and a tailing.INTRODUCTIONThe lead concentrate produced from Mount Isa ores can vary from 20 to 50 per cent lead, depending on the locality in the mine from which the ore is obtained. Variations of this order are independent of ore grade and lead recovery. The large variation is related to the presence in the ore of a variable fast floating low grade fraction known locally as the carbonaceous fraction because of its association with graphite. During conventional lead flotation with sodium ethyl xanthate the carbonaceous fraction floats rapidly and unselectively with normal Mount Isa galena.The paper discusses mainly the examination and treatment of an average carbonaceous fraction, defined here as the fast floating material in the mill feed of late 1956. The ore was drawn from the Mount Isa Black Star orebodies. The fraction represented about 5 per cent of the total ore...

Jan 1, 1961